Compressor Shut off When Cool Outside

[fog runner]

Hello,

I have a 2 story home with a seperate unit on the first and second floor. The first floor unit is a 3 ton Amana prestige unit. The unit works great except for when the outdoor temperature drops. So if a cool front comes through and the outside air drops down into the 50's at night, but the inside temperature is still warm (this happens often in the south) the AC unit will turn on to cool the inside and the compressor will start, but then after about 30 seconds or so the compressor will shut back off. The inside blower continues to run. After some set amount of time the compressor will try to start again and do the same thing. This will happen over and over. I have to shut the unit off. I checked the control signal to the compressor and it is still on. I also do not have this problem when the outside temperature is warmer, the unit starts and runs fine. I am not sure of what the exact outdoor temperature is when this will start, but I do know that if it is about 65 everything works fine and somewhere below 60 is where this issue occurs. The upstair unit which is the same unit in a 2 ton version does not have this issue. Can anyone give me any feedback on what may be causing this. Any information would be greatly appreciated.

[JonesHVAC-R]

Hello,

I have a 2 story home with a seperate unit on the first and second floor. The first floor unit is a 3 ton Amana prestige unit. The unit works great except for when the outdoor temperature drops. So if a cool front comes through and the outside air drops down into the 50's at night, but the inside temperature is still warm (this happens often in the south) the AC unit will turn on to cool the inside and the compressor will start, but then after about 30 seconds or so the compressor will shut back off. The inside blower continues to run. After some set amount of time the compressor will try to start again and do the same thing. This will happen over and over. I have to shut the unit off. I checked the control signal to the compressor and it is still on. I also do not have this problem when the outside temperature is warmer, the unit starts and runs fine. I am not sure of what the exact outdoor temperature is when this will start, but I do know that if it is about 65 everything works fine and somewhere below 60 is where this issue occurs. The upstair unit which is the same unit in a 2 ton version does not have this issue. Can anyone give me any feedback on what may be causing this. Any information would be greatly appreciated.

How old is the unit? Is the compressor hot when it shuts down? You may need to call a certified technician to open the unit to check this as we don't recommend the HomeOwner to do this. You can more than likely find a certified technician through our contractor locator link.

[mlc1955]

What mode of operation are you asking for, cool or heat and are these heat pump systems. If you are asking for the system to cool in the cooler weather this could drive the suction pressure down and possibly shut the compressor off and when the pressure rises it will restart. Since 1 system is doing it and the other is not then the system with the problem could be low on freon which will enhance the issue.
Just need more info on type of system and mode of operation.

[BaldLoonie]

Sounds like a low pressure safety doing its job. An A/C cooling in cool weather needs a head pressure control to keep system pressures up. This is added to units used in commercial buildings when they want to pay for cooling when it is cool. Sounds like you will need it added to your unit.

[superfittertech]

or when its cooler outside, just try opening the windows

[fog runner]

Thank You everyone for the replys. The compressor is not hot when it does this, it does it right when it gets the call for cooling, it starts up and runs briefly then shuts down.
The units are not heat pumps, but this is happening during the cooling cycle. Yes, the unit is getting the call for cool when it does this. The unit is a few years old and has been doing this pretty much since the first cool weather after install. I called the installer back out and they checked the unit/freon etc. and said everything look fine. They also said they would have to actually see the unit do this in order to diagnose, which is not likely to happen beings it usually happens at night when the temperature drops. Sounds like it could be this low pressure safety. I will just keep doing what I have been doing and just shutting the unit off when it gets to this point. In most places this isn't an issue, but down here is south Louisiana, it is February and the weather is perfect for causing this right now, 70's in the day and 50 at night.

[beshvac]

:ditto:
AC is not designed to run in low temperatures without a low ambient kit. The system is most likely tripping on low pressure. If you want it to run in 50 deg or less temperatures, I would recommend a low ambient kit.

[keeplearnin]

or when its cooler outside, just try opening the windows

yea great idea unless there are no windows and their are cooks hovering over stoves and whatnot then have a dining room full of drunks. Its getting hot in here!!!!!!!!!!!!!!!!!!!

[skippedover]

yea great idea unless there are no windows and their are cooks hovering over stoves and whatnot then have a dining room full of drunks. Its getting hot in here!!!!!!!!!!!!!!!!!!!

The OP was referencing a residential application, not commercial. Those of us in the industry do understand about commercial applications and invariably install low-ambient kits to any equipment on which it is not factory installed. Most houses/condos/town houses and other residential applications do have operable windows for cold weather operations and most homeowners would prefer to pen the windows to paying the power company for the privilege of operating the AC equipment. But for those who choose to operate the equipment, the low ambient kit is a requirement for most manufacturers when the OAT is less than 50° for sometimes 55°F OAT.

[beenthere]

Louisvilleairhvac, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

You can find the rules for posting and qualifications here (http://hvac-talk.com/vbb/showthread.php?t=957002).




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[beenthere]

71CHOPS, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

You can find the rules for posting and qualifications here (http://hvac-talk.com/vbb/showthread.php?t=957002).